· SDDS stands for "Self Describing Data Sets."· SDDS is just a standardized way to store and access data, i.e., a "file protocol."· SDDS also refers to a group of ~85 programs that use this file protocol.· These programs are the "tools" in the SDDS Toolkit.

· A hammer, a saw, a drill, etc., can be used together or sequentially to create and modify physical objects. · The programs in the SDDS toolkit can be used to sequentially transform SDDS data sets.

· Within some limits, it isn't determined ahead of time what physical objects can be modified or what can be created.· SDDS toolkit programs are generic and operate on any SDDS data set. The meaning of the operations is not predetermined.· Both physical and SDDS tools can be used in arbitrary sequences of arbitrary length. The capability of the toolkit grows very rapidly with the number of tools.

· Every new tool that is created makes the existing ones more useful, without any advance planning or coordination by developers.

· A new tool need not be useful by itself in order to be very useful as part of a toolkit.
Most SDDS tools produce no directly useful result. This freedom makes new tools much easier to create.

· Because the SDDS tools are commandline driven, they can be embedded in scripts..· Tcl/Tk is used to make graphical user interfaces (GUIs) that depend on SDDS tools for computational "muscle," data collection, and data display.· Engineers and physicists can use SDDS tools directly to develop new algorithms. Once finished, those results can easily be put into a GUI script.

· Self-describing data files require more information in the file besides the data itself.· At minimum, a self-describing file protocol· requires that every data element in the file has a name.· forbids access to data except via the name.

· SDDS is a specific self-describing data protocol, developed at APS for accelerator commissioning.· Highly successful application of SDDS to commissioning lead to its use for operations.· An SDDS file consists of· A file header describing a structure composed of an arbitrary number of parameters and arrays, and a data table of arbitrary rows and columns.· Zero or more instances of the structure.· There are many extremely general self-describing file protocols around today.· In using these protocols, users find it necessary to create elaborate data standards of their own, which inhibits use of the toolkit approach.· In contrast, the SDDS file protocol is simple enough to be used in "daily life," but general enough to be widely useful.· Only the simplicity of the data model makes the SDDS Toolkit feasible.

· IPNS---Used for data logging, analysis, and display.· CEA (France)---Used by a group of particle physicists doing underwater experiments in the Mediteranean.· SRRC (Taiwan)---Installed by request.· LEDA (LANL)---Installed by request.· CEBAF (TJNAF)---Installed by request.